1. Field of the Invention
The present invention relates to a vehicle interior material, and more specifically, to a vehicle interior material employed on the vehicle compartment side of a vehicle panel, such as a front pillar or a roof side rail of an automobile.
2. Description of the Related Art
As shown in FIG. 13 this kind of vehicle interior material is used for example for a front pillar garnish 101F or a roof side rail garnish 101S employed on the vehicle compartment side of a vehicle panel, such as a front pillar 105F or a roof side rail 105S of an automobile 100. Besides aesthetic reasons with regard to the vehicle compartment, these vehicle interior material are used because they can deform plastically when directly hitting a portion (e.g. the head) of a passenger""s body, for example in the course of a collision of the vehicle, so that the impact force inflicted on the passenger from outside the vehicle can be absorbed and dampened.
As shown in FIG. 14, a conventional front pillar garnish 101F, as disclosed for example in JP H9-175284A1 includes a facer 102 with a substantially C-shaped cross-section, a plate-shaped vertical rib 103L extending in the longitudinal direction on the rear side of the facer 102, and a plurality of also plate-shaped horizontal ribs 103W, intersecting at substantially right angles with the vertical rib 103L and bridging the walls on the two sides of the facer 102. The front pillar garnish 101F is fastened with the ribs being in contact with a protruding bar 107 of the inner panel that is part of the front pillar 105F.
However, with a front pillar garnish 101F having, as described above, a lattice structure made of a vertical rib 103L and a plurality of horizontal ribs 103W in the space on the rear side of the facer 102, the vertical rib 103L and the horizontal ribs 103W overlap when deforming and breaking down during an impact, and the height of the space that is provided mainly for the dampening of impacts (that is, the shock-absorbing stroke) is diminished by that amount. Thus, in order to maintain the high shock-absorbing capabilities verified by the head impact index according to U.S. standard FMVSS 201, it becomes necessary to increase the protrusion height of the ribs. Consequently, when the front pillar garnish 101F is attached to the front pillar 105F, the front pillar garnish 101F takes up more space of the vehicle compartment, which leads to the problems of a feeling of pressure on behalf of the passengers, an obstruction of the visual range, and an encumbrance when entering or leaving the vehicle.
JP H10-203278A1 discloses a front pillar garnish 101F wherein the vertical rib is eliminated from the rear side of the facer 102 covering the protruding bar 107 of the front pillar 105F, as shown in FIG. 15. Moreover, notches 104 opened in opposition to the region 108 where the protrusion end face 107a of the protruding bar 107 abuts the passenger-opposing lateral face 107b formed in continuation on one side thereof are formed in horizontal ribs 103W that are arranged independently.
With such a front pillar garnish 101F in which the vertical rib has been eliminated, the decrease of the impact absorption stroke due to overlapping of the ribs as described above can be prevented, the notches 104 provided in the horizontal ribs 103W absorb the impact force while forming cracks originating at the bottom portions of the notches and extending toward the facer 102, and the entire ribs buckle and absorb the impact, so that the shock-absorbing capabilities are better than when the horizontal ribs are not provided with notches 104. As a result, the protrusion height of the ribs can be decreased, and the amount that the front pillar garnish 101F bulges into the vehicle interior can be diminished.
However, in the front pillar garnish 101F as shown in FIG. 15, which attempts to absorb the impact by providing one notch 104 at a position opposing the passenger and primarily receiving the impact, and forming a crack originating at the bottom portion of this notch 104 as described above, there is a certain limit to the increase of shock-absorbing capabilities due to the selection of the material, and it is not possible to reduce the maximum protrusion height of the ribs to less than about 18 mm.
Conventionally, various contrivances have been employed to increase the shock-absorbing capabilities, such as providing the rear side of the pillar garnish with a separate shock-absorbing cushion material, and molding the entire pillar garnish from a thermoplastic resin with excellent shock-absorbance, but these contrivances brought about the problem that as the down-side of increasing the shock-absorbing capabilities, the costs rise in the same degree.
The present invention has been contrived with this state of the art in mind, and it is an object of the present invention to provide a vehicle interior material that efficiently dampens impact forces with ribs protruding into a limited space enclosed by a vehicle panel and a facer, and that reduces the protrusion height of the ribs, thereby curbing the amount that the vehicle interior material bulges into the space of the vehicle compartment.
As the result of concerted efforts to solve the afore-mentioned problems, the inventors have recognized that high shock-absorbing capabilities can be maintained in a limited space by eliminating the vertical ribs that are conventionally employed for pillar garnishes and using a configuration that can be logically deformed or buckled when a passenger exerts an impact on the horizontal ribs, thereby arriving at the present invention.
In other words, the present invention provides a vehicle interior material including
a facer with a substantially C-shaped cross-section covering a panel ridge on the vehicle compartment side of a vehicle panel, the panel ridge having a protrusion end face extending in a longitudinal direction and two lateral faces in continuation of the end face, a space being provided between the panel ridge and the facer; and
a plurality of ribs, which are arranged independently from one another, bridging side walls of the facer, the ribs protruding from a rear face of the facer opposite the vehicle panel into the space and intersecting with the longitudinal direction of the vehicle panel;
wherein the shape of a protruding edge of the plate-shaped ribs substantially follows at least a protrusion end face of the panel ridge and the passenger-opposing lateral face formed in continuation thereof to one side; and
wherein the vehicle interior material further comprises a deformation-inducing means, causing a portion of the plate-shaped ribs protruding towards the protrusion end face of the panel ridge to buckle at an intermediate protrusion position when subjected to an impact by a passenger.
With such a vehicle interior material, the plate-shaped ribs are independent from one another, so that the decrease of the actual impact absorption stroke due to overlapping of the ribs can be prevented, while the deformation-inducing means with which the ribs are provided cause multi-stage deformation and break-down starting the buckling at an intermediate portion of the ribs before the ribs buckle along the protrusion base end, the protrusion height of the plate-shaped ribs can be curbed and the plate-shaped ribs display efficient shock-absorbing characteristics maintaining a low impact acceleration.
When the deformation-inducing means includes a main notch opened in the protruding edge of the plate-shaped ribs in opposition to a region where the protrusion end face of the panel ridge abuts against the passenger-opposing lateral face formed in continuation on one side thereof, and one or more auxiliary notches provided in the protruding edge of the plate-shaped ribs in opposition to or nearly opposite the region where the protrusion end face of the panel ridge abuts against the lateral face formed in continuation on the other side thereof, then the buckling of the ribs is induced along a virtual line connecting a bottom portion of the main notch and a bottom portion of the auxiliary notch, or along a virtual line connecting the bottom portions of a plurality of auxiliary notches on which a large impact force is exerted, and the bottom portions of the main notch and the auxiliary notch(es) become the starting points for cracks towards the facer. The formation and progress of these cracks contributes to a more efficient shock absorbance.
When the deformation-inducing means includes a main notch provided in the protruding edge of the plate-shaped ribs in opposition to a region where the protrusion end face of the panel ridge abuts against the passenger-opposing lateral face formed in continuation on one side thereof, and one or more step portions provided in the protruding edge of the plate-shaped ribs in opposition to or nearly opposite the region where the protrusion end face of the panel ridge abuts against the lateral face formed in continuation on the other side thereof, then the buckling of the plate-shaped ribs is similarly induced along a virtual line connecting a bottom portion of the main notch and a bottom portion of the step portion, or along a virtual line connecting the bottom portions of a plurality of step portions on which a large impact force is exerted, and the bottom portions of the main notch and the step portion(s) become the starting points for cracks towards the facer.
When the deformation-inducing means includes a main notch provided in the protruding edge of the plate-shaped ribs in opposition to a region where the protrusion end face of the panel ridge abuts against the passenger-opposing lateral face formed in continuation on one side thereof, and one or more thin-walled portions provided in the protruding edge of the plate-shaped ribs in opposition to or nearly opposite the region where the protrusion end face of the panel ridge abuts against the lateral face formed in continuation on the other side thereof, then the impact is absorbed by the generation of cracks in the thin-walled portion(s), the buckling of the plate-shaped ribs is similarly induced along a virtual line connecting a bottom portion of the main notch and a bottom portion of the thin-walled portion, or along a virtual line connecting the bottom portions of a plurality of thin-walled portions on which a large impact force is exerted, and the bottom portions of the main notch and the thin-walled portion(s) become the starting points for cracks towards the facer.
When the vehicle interior material is provided with a thin-walled portion instead of the main notch, and the thin-walled portion has the same cross-section as the main notch, then impacts are absorbed by cracks occurring at the thin-walled portion, the buckling of the plate-shaped ribs is similarly induced along a virtual line connecting a bottom portion of the thin-walled portion with the bottom portion of the auxiliary notch, a bottom portion of the step portion or a bottom portion of another thin-walled portion, or along a virtual line connecting bottom portions of the same kind or the surroundings of bottom portions, and the bottom portion of the thin-walled portion, and the afore-mentioned bottom portions of the auxiliary notch, the step portion and the thin-walled portion become the starting points for cracks extending toward the facer.
When at least one virtual line extending from at least one structural portion of the deformation-inducing means toward the facer partitions the plate-shaped ribs into at least two portions of different thickness distribution along a protrusion direction and average thickness, then the shock absorbance characteristics of the plate-shaped ribs can be adjusted even freer, and impact forces can be dampened efficiently in the space limited by the vehicle panel and the facer. If the overall average thickness of the plate-shaped ribs is in the range of 0.8 to 2.8 mm, then these high shock absorbance characteristics can be maintained. If the average thickness is less than 0.8 mm, then, when the plate-shaped ribs are subjected to an impact, they can be easily pushed to the bottom onto the facer before sufficiently dampening the impact, and as a result it becomes difficult to sufficiently absorb and dampen the impact. On the other hand, if the average thickness is more than 2.8 mm, then the buckling strength of the plate-shaped ribs becomes too large, so that the impact acceleration when subjected to an impact becomes large, and it becomes difficult to maintain the required impact absorbance characteristics.
To efficiently absorb and dampen impacts with an inventive vehicle interior material of the above configuration, it is possible to mold the facer and the plate-shaped ribs in one piece by injection molding using the same thermoplastic resin, which greatly reduces costs compared to conventional materials, which employ the double injection molding method using different resins to increase the shock absorbance characteristics or provide a separate shock-absorbing material on the rear side of the facer in addition to the ribs.
The vehicle interior material of the present invention is preferably used as a center pillar garnish or a roof side rail garnish of a vehicle.